Glow tube cathode support



March 17, 1953 HANCOCK 2,632,128

GLOW TUBE CATHODE SUPPORT Filed Jan. 9, 1951 172g: 4 5 METAL PatentedMar. 17, 1953 UNITED STATES PATENT QIFIFICFE .GLOW TUBE CATHODE SUPPORTRobert Dgflancock, Compton, Calif., assignor to ,NorthropAircraft, Inc.,Hawthorne, .Calif .a

,corporationof California Application] anuary 9, 1951, Serial No.205,128

A. Claims.

This invention refers'to ionic "glow tubes, especially glow tubeswherein a plurality of cathodes 'are employed to render an indicationofa concuit is desired and is'so indicated by'causing a "selectedgroupof cathodes, that are in the configuration "of a 'desiredsymbol, to beenergized. Such tubes areknown as read-'out'tubes. If

the cathodes are suspended in' the gaseous medium by lead wires orspecial suspension wires, the tube is susceptibleto damage due tobending or breaking of the cathodes resulting from high accelerations.

It is, accordingly, an object of the'present invention to provide amulti-cathode ionic glow tube wherein the cathodes are rigidlymaintained in a desired spatial relationship.

It is another object ofthe present invention toprovide a means-andmethod of confining a cathode glow, in a glow tube, 'to that portion ofa cathode that is visible from one direction.

Briefly, the tube of the present invention may be constructed in thefollowing ways: (a) The electrodes can be formed of bars of a conductingmaterial with suitable lead wires attached thereto, these bars beingcast in an insulating material to form a solid block, thereby rigidlymaintaining the electrodes in a desired position and electricallyinsulated from each other. (22) The cathodes can be formed of bars ofconducting material, with a coating of insulating material thereon, thecathodes then being cast in a block of conducting material, a part ofeach cathode being exposed. In this latter case the conducting materialmatrix may be employed as an anode for the embedded cathodes.

In the drawings,

Figure 1 is a perspective view of a tube embodying the presentinvention.

Figure 2 is a cross sectional fragmentary view of two steps in theembedding of a cathode.

Figure 3 is a cross sectional fragmentary view of a modification of myinvention.

Figure 4 is a cross sectional fragmentary view of another modificationof my invention.

Referring to Figure 1, an envelope l is provided at least with an endwindow 2 of transparent material, such as glass, and at the opposite endwith a re-entrant stem 3. In this embodiment, a ceramic plate 4 ispositioned in the envelope i parallel to the window 2, this plate 4having embedded therein a plurality of electrically separate cathode,sections 5, each havinga portionexposed to the gas in the envelope.

This gas is preferablyanoble gas at glow discharge pressure, "such asfor example, neonxat 20 mm. Hg pressure.

Each of the cathode sections 5 is connected by a lead 6 to the outsideof the tube through "stem 3, and each lead is covered with glass tubingor ceramic paint 1 to prevent aglow discharge from occurring thereon.The plate 4 is firmly supported by the leads 6.

A ring anode 8 is also supportedfrom stem .3 .and plate t by anode lead9. and is positioned between the'plate l and window 2, being sufii-.ciently large in diameter so that view' of the as shown in Figure 2a,preferably with leads 6 already attached to the cathode sections 5. The

casting surface ii! opposite the leads 6 is then ground or otherwiseprocessed to form a flat surface lila to expose a portion of eachcathode section 5 as shown in Figure 2b. The cast plate is then mountedin the tube as shown in Fi ure 1.

When a potential source is connected to selected groups of cathodesections, these sections will glow, and, in accordance with the cathodesection pattern used, various intelligible symbols, such as numerals andletters, will be made visible. The particular cathode pattern shown inFigure 1 will permit all the numerals and many letters to be formed. Thepresent invention, however, is not to be limited to use in anyparticular cathode section pattern.

As it may be advantageous in some instances to have the anode of thetube equi-distant from all parts of the cathode sections, in order toobtain a uniform glow along any energized cathode section, the anode canbe in the form of a thin conductive sheet l2 positioned on the groundsurface ll] of the plate 4, as shown in Figure 3, with openings l3therein, through which the cathode sections 5 are exposed. The edges ofthe openings I3 are spaced from the cathode sections so that no shortcircuit can occur when the tube is energized. The opening edges are alsopreferably uniformly spaced from the cathode sections to insure uniformglow thereon.

As shown in Figure 4, the same condition can also be obtained by firstcoating the cathode sections 5 with insulating material l4 and thencasting these coated sections in metal to form a metal plate 412, thisplate then being faced off to expose the cathode sections. The metalplate 4b is then mounted in the envelope l in place of plate 4. with thecast metal connected as the tube anode. The insulating material M thenforms both the insulation between cathode and anode and the means tohold the cathode sections in place in the anode.

In any case, the cathode sections are firmly held in place, with onlythe face thereof to be viewed exposed to the gas in the tube. In thisway. only the cathode area to be viewed need be energized to produce aglow thereon. Current drain in the tube is thereby reduced.

From the above description it will be apparent that there is thusprovided a device of the character described possessing the particularfeatures of advantage before enumerated as desirable, but whichobviously is susceptible of modification in its form, proportions,detail construction and arrangement of parts without departing from theprinciple involved or sacrificing any of its advantages.

While in order to comply with the statute, the invention has beendescribed in language more or less specific as to structural features,it is to be understood that the invention is not limited to the specificfeatures shown, but that the means and construction herein disclosedcomprise a preferred form of putting the invention into effect, and theinvention is, therefore, claimed in any of its forms or modificationswithin the legitimate and valid scope of the appended claims.

What is claimed is:

1. In a glow tube having an envelope includ ing a transparent window,said envelope being filled with a gas at cathode glow dischargepressure, an anode in said envelope, 2. plate having a planar surfacefacing said window, a plurality of cold cathodes having their longestdimension extending in the plane of said surface, said cathodes beinginsulated from each other with each cathode embedded in said plate witha surface corresponding to said longest dimension exposed to said gasand positioned to planar with the surface of said plate, leads from saidcathodes extending through said plate on the opposite side thereof fromsaid exposed cathode surfaces and insulated from each other, the exposedsurfaces of said cathodes being arranged in a pattern such that whenselected groups of said cathodes are energized as cathodes, intelligiblesymbols such as numbers and letters will be visible through said windowby the combination of cathode glows on the exposed surfaces of thecathodes in the groups energized.

2. Apparatus in accordance with claim 1 wherein said plate is entirelyof insulating material.

3. Apparatus in accordance with claim 1 wherein said plate is entirelyof insulating material and wherein said anode is a conductive layermounted on said planar plate surface and having edges adjacent butspaced from the exposed surfaces of said cathodes.

4. Apparatus in accordance with claim 1 wherein said plate is ofconductive material and wherein a layer of insulating material ispositioned between the embedded portion of each cathode and the leadtherefrom and the conductive material of said plate, said plate havingan external lead seal through said envelope whereby said plate can beconnected as an anode.

ROBERT D. HANCOCK.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,038,825 Canady Apr. 28, 19362,142,106 Boswau Jan. 3, 1939

